Abstract tool lineage handling out of ToolBox.
Start work on infrastructure to support tool lineages not defined within the tool shed install model.
Abstract out higher-level helpers in ToolBox for lineage reasoning.
Reduces code duplication slightly and simplifies __add_tool_to_tool_panel (cyclomatic complexity reduced from 20 to 14).
Fix unit tests for 7cee92f.
Bugfix: Apply tool panel filtering in workflow editor.
Bug originally reported by Eric here - http://dev.list.galaxyproject.org/Bug-Toolbox-filters-not-applied-in-workflows-td4662879.html (though this only fixes the superficial bug of them showing up in the workflow editor - and does not yet implement "strong" toolbox filters as requested).

This is actually a broader change that centralizes logic for listing out tool panel contents when displaying components to the user and the added filtering comes about from that. It also eliminates the last places Galaxy was accessing toolbox.tool_panel directly (in those mako templates).
Update attributes and methods to reflect effort to hide ToolBox details.